CCN1 Combustion and Ventilation

Question 1

What are the three elements required for combustion to take place, commonly known as the 'fire triangle'?

Accepted Answer

Fuel, oxygen, and ignition (heat)

Answer

Gas, electricity, and water

Answer

Fuel, nitrogen, and pressure

Answer

Gas, air, and a flue

Question 2

What is the ideal CO₂ reading for natural gas when an appliance is correctly set up for complete combustion?

Accepted Answer

9-10%

Answer

5-6%

Answer

7-8%

Answer

12-14%

Question 3

What is the minimum free area of ventilation required for an open-flued gas appliance with a rated input over 7 kW in a room?

Accepted Answer

5 cm² per kW of rated input above 7 kW

Answer

5 cm² for every kW of rated input

Answer

10 cm² per kW of rated input above 7 kW

Answer

No additional ventilation is required

Question 4

What dangerous gas is produced as a result of incomplete combustion of natural gas?

Accepted Answer

Carbon monoxide (CO)

Answer

Carbon dioxide (CO₂)

Answer

Nitrogen dioxide (NO₂)

Answer

Sulphur dioxide (SO₂)

Question 5

A room-sealed gas appliance draws its combustion air from where?

Accepted Answer

Directly from outside the building through a duct or balanced flue

Answer

From the room in which it is installed

Answer

From an adjacent room via an air vent

Answer

From the loft space above the room

Question 6

What is the approximate air-to-gas ratio required for the complete combustion of natural gas?

Accepted Answer

10:1

Answer

5:1

Answer

15:1

Answer

20:1